Took my first buck Thursday night, second day of the season. I have never tried hunting out of a tree stand for more than thirty minutes before and forced myself to try it seriously this season. Waited through about 30 does for the two hours I was up before a little 8 pointer walked right underneath me. .280'ed him at a whopping 5 yards. I was really dumbfounded about how oblivious he was to my presence. I had been watching some does through my scope about 150 yards down a milo field and had my scope cranked up to nine when he came walking up. I pulled up on him and couldnt see anything but a brown blur. Dropped the rifle back down a little and turned the scope down as far and as fast as I could, put the rifle back up to my shoulder and squeezed one off. He never seen or heard anything. I have a whole new respect for being downwind and up in the air a little bit. This is probably nothing new to a bow hunter but it really amazed me.

Most will not notice you unless you move but every now then you will have one look dead at you for some reason. When this happens I usually freeze except for slipping the safety off. They may look away and back a couple times. Each time they look away move the rifle a little in the right direction. The next look away is the time to drop him. It helps to wear a camo knit to cover your shiny face unless you have a beard.
Good Luck on the next one.

My Dad has a friend who used to be a shop teacher in VT. Told his class once that he hunted with a cinder block. Got the deer close like you did and dropped it on his head. They liked that. (He was kidding, of course). Congrats on your buck.